1. Field of the Invention
The present invention relates to a pressure device for a pinch roller of a video cassette recorder (hereinafter "VCR") and more particularly, to a pressure device for a pinch roller which is simple in structure so that the pressure device can efficiently improve its operation and productivity with low cost, and contribute to the simplification of VCR.
2. Description of the Prior Art
Various types of pressure devices for a pin roller of a VCR are well known in the art. One of such prior art pressure devices as shown in FIGS. 1 to 4 has a complicated structure. The conventional pressure device includes a function arm 2 disposed under a main chassis 1 for rotating by itself about a first shaft pin 3, on one end of the function arm 2, a function plate 4 is disposed for reciprocally moving through a guide pin in the direction indicated by arrow A as shown in FIG. 1. Since a locking pin 6 of the function plate 4 is inserted into a locking hole 2a of the function arm 2, the function arm 2 rotates in accordance with the movement of the function plate 4.
On the other end of the function arm 2, a first connecting pin 2b protrudes upward through a guide hole 1a of the main chassis 1. The first connecting pin 2b is provided with a first link 8 rotatably connected to the first connecting pin 2b at one end of the first link 8 to be always pressed to the left side of the drawing by elastic force of a first tension coil spring 7. Second and third links 9 and 10 are rotatively connected to the other of the connecting pin 2b through a second connecting pin 11.
A pinch lever 14 is connected to the second link 9 by a third connecting pin 15 and which is rotatably mounted on the main chassis 1 by means of a second shaft pin 12 of a pinch guide hole 14a and is resiliently supported by elastic force of a second tension coil spring 13 so that the second link 9 rotates in the clockwise direction. A pinch arm 19 having a pinch roller 18 which is pressed against a capstan shaft 17 is connected to the other of the third link 10 by a fourth connecting pin 20 and is rotatably mounted on a third shaft pin 16 of the main chassis 1.
Accordingly, as shown in FIG. 1, when play mode signals (not shown) of the conventional pressure device for the pinch roller of the VCR are applied in a stop mode while the pinch roller 18 is some distance away from the capstan shaft 17, the function plate 4 driven by a drive source (not shown) moves in the direction indicated by arrow A. Since the locking pin 6 of the function plate 4 is inserted in the locking hole 2a of the function arm 2, the function arm 2 rotates in a clockwise direction about the first shaft pin 3. And the first link 8 connected to the first connecting pin 2b of the function arm 2 overcomes elastic force of the first tension coil spring 7 and moves from the state shown in FIG. 1 to the state shown in FIG. 2. At the same time, the pinch lever 14 connected to the second link 9 overcomes the elastic force of the second tension coil spring 13 and rotates about the second shaft pin 12 in the counterclockwise direction. The pinch arm 19 connected to the third link 10 revolves in the counterclockwise direction about the third pin 16, thereby forcing the pinch roller 18 of the pinch arm 19 to contact the capstan shaft 17. At this point, the elastic force of the second tension coil spring 13 which supports the pinch lever 14, delivers the pressure force and forces the pinch roller 18 to press against the capstan shaft 17 as well. Additionally, the elastic force of the first tension coil spring 7, which supports the first link 8, works as the restoring force when the pinch arm 19 returns from the play mode to the stop mode.
However, the conventional pressure device for a pinch roller of a VCR has many components involved in the series of procedures by which the reciprocation movement of the function plate 4 is converted to a pressure movement which forces the pinch roller 18 to press against the capstan shaft 17. As a result, this large number of parts, and attendant cumulative size tolerances for the individual parts, reduce reliability of operation. In addition, large numbers of component parts increase production cost, decrease productivity, and hinder minimization of the sizes of products.